The Eye Structure

External Parts of the Eye

(Tear Duct)

1. Sclera

White part of the eye

Is made of tough tissue

Protects the inner workings of the eye and gives the eye its shape

2. Cornea

The curved, clear, outer surface

Covers the iris and pupil

3. Aqueous Humor

A clear, watery fluid

Circulates in the front part of the eye, maintaining a constant pressure inside the eye.

4. Pupil

Is the opening in the center of the iris

The size of the pupil: determines the

amount of light entering the eye

controlled by circular muscles

5. Iris

The colored part of the eye

Made of circular muscles

Controls the size of the pupil

6. Lens

A clear convex lens

Is responsible for focusing light to form an image on the retina

Can change shape to focus on nearby and distant objects

7. Vitreous Humor

A clear, jelly-like substance

Fills the eye behind the lens

Holds the structures of the eye in place

Maintains the shape of the eye

8. Optic Nerve

A thick bundle made of millions of neurons

Carries visual information from the retina to the brain.

9. Retina

A thin, translucent, light-sensitive tissue made of specialized cells called rods and cones

Receives images formed by the lens

10. Optic Disc

The point where the optic nerve enters the retina

NOT sensitive to light

Known as the “blind spot”

11. Tapetum

A shiny layer that lines the area behind the retina of many animals

Helps make animal eyes visible in the dark

Allows them to see better at night

Vision

Corrective Lenses (Glasses & Contacts)

Near Sighted

Far Sighted

Color Blindness

Your eyes have special cells called rods and cones

Rods – Light sensitive

Cones – Color Sensitive

Color Blindness

There are three main kinds of color vision defects. Red-green color vision defects are the most common. This type occurs in men more than in women. The other major types are blue-yellow color vision defects and a complete absence of color vision.

Color Blindness

Most of the time, color blindness is genetic. There is no treatment, but most people adjust and the condition doesn't limit their activities.

LASIK

1. Create a flap of corneal tissue

2. Remodel the cornea using the laser

3. Reposition the flap